The present invention relates to coaxial cable connectors and, more particularly, to a coaxial connector having an improved crimp section.
Coaxial cable connectors are commonly used to terminate coaxial cables. These connectors typically include a conductive outer shell comprising a mating section, a signal pin and a cylindrical sleeve that receives and mechanically secures a stripped end of a coaxial cable. The coaxial cable has a center conductor for transmitting a signal. The center conductor is surrounded by a dielectric. An outer ground or shield conductor in the form of a pliant wire braid encircles the dielectric. The outer conductor is encased in a protective jacket.
To secure the coaxial cable in the connector, a stripped end of the coaxial cable is inserted into a receiving end of the cylindrical sleeve. The exposed center conductor is electrically connected to the signal pin contained within the connector. As the coaxial cable is inserted into the cylindrical sleeve, an inner tubular member, that may comprise raised barbs, is forced between the dielectric and the outer conductor of the coaxial cable. The outer conductor is received in a space between the cylindrical sleeve and the inner tubular member and may be folded back over the end of the protective jacket. This method and arrangement is disclosed in U.S. Pat. No. 5,499,934 issued to Jacobsen et al. and U.S. Pat. No. 5,525,076 issued to Down. A conventional crimping tool is then used to apply a crimp to the outside of the cylindrical sleeve securing the outer conductor jacket of the coaxial cable between the inner tubular member and the cylindrical sleeve.
A known alternative method for securing a coaxial cable in a connector is commonly used when larger connectors terminate smaller coaxial cables. In this method, a ferrule and an insulative cylinder, respectively, are positioned over the stripped coaxial cable before insertion into the cylindrical sleeve. The exposed center conductor is electrically connected to the signal pin within the connector. The outer conductor of the coaxial cable is then folded back and over the ferrule so that the outer conductor is received in a space between the cylindrical sleeve and the ferrule when the coaxial cable is inserted into the cylindrical sleeve. A conventional crimping tool is then used to apply a crimp along the outside diameter of the cylindrical sleeve to secure the outer conductor jacket of the coaxial cable between the ferrule and the cylindrical sleeve.
In these connectors, a compressive force applied by the crimp secures the internal components of the connector. This retention alone, however, is inadequate when external pulling forces are applied to the coaxial cable. For example, when an external force is exerted on the coaxial cable in a direction opposite from the connector body, the compressive forces are unable to prevent outward movement of the internal components. When the internal components become displaced, the integrity of the connector is jeopardized. Gaps created between the internal components also allow moisture and other foreign matter to enter the connector and may result in pin stubbing upon mating, further deteriorating the electrical performance of the connector.
It is therefore desirable to develop a coaxial connector with a rigid construction that improves coaxial cable retention and electrical performance by providing additional physical restraint of the internal components of the coaxial connector.
An object of the present invention is to develop an improved crimp section for a coaxial cable connector. This and other objects of the invention are achieved by a coaxial connector having a conductive outer shell comprising a mating section and a cylindrical sleeve. The cylindrical sleeve has a cable receiving end for receiving a cable, at least one ferrule located inside the cylindrical sleeve and an annular projection positioned on the cable receiving end of the cylindrical sleeve. The annular projection has a larger external diameter than the cylindrical sleeve. When a crimping die is applied to the cylindrical sleeve, the crimping die first contacts the annular projection, causing the annular projection to roll inward and toward the -mating section of the conductive outer shell to securely forward bias the cable and ferrule within the cylindrical sleeve.